1. Field of the Invention
The present invention is related to a storage system and an operation method of a storage system, and particularly to a storage system and an operation method of a storage system that have advantages of fast establishment, recovery, reshaping, and/or resizing.
2. Description of the Prior Art
A high level storage device is usually capable of providing a very large capacity file system and redundant array of independent disks (RAID) for a user. However, when the very large capacity file system is built in a large capacity RAID, data of the user stored in the large capacity RAID may suffer some risk in some conditions.
RAID level greater than 1 can still provide normal write and read capability when one disk of the RAID fails (“degraded”), but RAID-6 can allow at most two disks to fail. When a RAID (such as the RAID-1, the RAID-5, or the RAID-6) has a failed disk, the user can substitute the failed disk with a normal disk. Meanwhile, a program of an operation system (such as Linux) will perform a recovery process (called recovery) on the normal disk. Then, the program can store data (the same as data stored in other healthy disks) in the normal disk according to a store rule of the RAID. While the program performs the recovery process on the normal disk, the RAID is unsafe because the RAID (except for the RAID-6) can not allow another disk to fail. However, the RAID spends more time on the recovery process the greater the capacity of the RAID, which means that the RAID is unsafe for a longer time. Thus, when a file system is in a degraded RAID, risk of loss of user data of the file system is increased because the RAID may crash at any time.